Synthesis of a monoclinic BiVO4 nanorod array as the photocatalyst for efficient photoelectrochemical water oxidation

Abstract

BiVO4 is one of the most efficient photocatalysts for promoting water oxidation under the framework of Z-scheme water splitting due to its small band gap feature. In this study, the BiVO4 nanorod array was successfully synthesized on fluorine-doped tin oxide (FTO) glasses via a simple solution method, and the electrode was applied as the photoanode for water oxidation. The highest photocurrent density of 0.12 mA cm−2 (measured at 1.23 V vs. RHE) and the smallest onset potential of 0.32 V vs. RHE were obtained for the optimized BiVO4 electrode under AM 1.5G illumination due to the rough surface for promoting light absorption and the one-dimensional (1D) pathway for accelerating the charge transfer, which benefitted from the rod-like structure. Electrochemical impedance spectroscopy was applied to analyze the charge-transfer resistance and electron lifetime of the system. The results suggest that the well-defined nanorod structure can be realized by simply tuning the reaction parameters, and this 1D nanostructure can simultaneously achieve high light absorption and a long electron lifetime, which favor the high photocatalytic ability for water oxidation.